The above image is typical of an individual who takes Nitroglycerin…an elderly gent in pain clutching their chest.

Nitroglycerin is another essential drug that is required to be in the emergency kit in the dental office. This drug is used to treat both acute angina and myocardial infarction. Let’s briefly discuss both of these conditions.

Acute Angina: This is a symptom of coronary artery disease. Those affected may experience a squeezing pressure, heaviness, tightness or pain in their chest. Coronary Artery Disease develops when the major blood vessels that supply your heart with blood containing oxygen and nutrients, become damaged or diseased. Deposits (also called plaques) containing cholesterol accumulates in your arteries over time. These plaques as well as inflammation are usually to blame for Coronary Artery Disease.

Myocardial Infarction: This is also known as a heart attack. It occurs when blood flow stops to a portion of the heart which in turn causes damage to the heart muscle. The most common symptom is chest pain; one can also feel discomfort which may travel into the shoulder, arm, back, neck or jaw.

Nitroglycerin’s Mechanism of Action
With both of the above conditions, the goal is to decrease the workload i.e. the ‘pumping action’ of the heart. This will help to reduce any undue stress on the heart.

Nitroglycerine acts by decreasing the venous return of blood to the heart: This results in a decrease in ‘load’ going to the heart which in turn translates into less stress on the heart, lowering its requirement to work hard. In essence, Nitroglycerin lightens the hearts workload. It helps to correct the imbalance in supply and demand of oxygen in the heart.

Contraindications of Nitroglycerin
Nitroglycerin is a relatively safe drug. It acts to lower blood pressure, so it shouldn’t be given if systolic blood pressure is less than 90. The normal range in blood pressure is 90-120 / 60-90. Note: The systolic number is the top range (90-120).

Dosage and Availability
Nitroglycerin can be administered in either a tablet form or as a spray. The tablet form of nitroglycerin has a shelf life of approximately three months once the bottle is opened and exposed to air and light. The spray form doesn’t lose its efficacy once it is opened. For a patient with existing angina, a patient usually has their nitroglycerin within reach in case symptoms arise. However if in the tablet form and if the bottle was opened over three months ago, it is likely that the Nitroglycerin will be inactive. This is why the dentist should have an unopened bottle in their emergency kit.
Note: Nitroglycerin is administered sublingually (under the tongue). Pain relief occurs within minutes.

Protocol for Administration
Nitroglycerin can be administered three times in total at five minute intervals; however, as stated previously, the systolic blood pressure must remain above 90.

In Closing
If there is no relief of symptoms with Nitroglycerin, then 911 should be called. Morphine can be administered to deal with the pain and aspirin is usually given to help prevent the formation of a blood clot. We will look at the role of aspirin in the next blog.